Move files added by AddVtkHyperTree into their modular location:

 {Filtering => Common/DataModel}/vtkHyperTreeCursor.cxx
 {Filtering => Common/DataModel}/vtkHyperTreeCursor.h
 {Filtering => Filters/HyperOctree}/vtkHyperTreeGrid.cxx
 {Filtering => Filters/HyperOctree}/vtkHyperTreeGrid.h
 {Graphics => Filters/HyperOctree}/Testing/Cxx/TestBinaryHyperTreeGrid.cxx
 {Graphics => Filters/HyperOctree}/Testing/Cxx/TestHyperTree.cxx
 {Graphics => Filters/HyperOctree}/vtkHyperTreeFractalSource.cxx
 {Graphics => Filters/HyperOctree}/vtkHyperTreeFractalSource.h

Change-Id: I7e4d02ca9a94e68b9e6e696770966ff4a7cc6176